METHOD FOR CURING AN EPOXY RESIN COMPOSITION CONTAINING REACTIVE PHOSPHONATE

Description

[0001] The present invention relates to a process for curing an epoxy resin composition according to claim 1 that can be used, for example, in printed wiring boards for electronic applications and that represents a novel improvement, for example, over the type of compositions described in Japanese Patent Publication No. 2001/302,879 to Shin Kobe Electric Manufacturing Co. Ltd. /Hitachi Chemical Co. Ltd. The present invention relates also to a process for the manufacture of an electric substrate material according to claim 5.

[0002] The composition of the present invention contains, as one essential component, an epoxy resin. This component is present at from about 20% to about 50%, by weight of the total weight of the composition. Preferably, this component is a non-halogen containing epoxy resin, such as a bisphenol A-type of epoxy resin, or other resins of this general type that have utility for the manufacture of printed wiring boards or other electronic substrate materials of that type (bisphenol F epoxy, phenolic novolak epoxy, cresol novolak epoxy, and/or bisphenol A novolak epoxy resins). Compatible mixtures of any of these resins may be employed.

[0003] An additional optional, but preferred, component for the compositions of the present invention is a polybenzox- azine resin in an amount of up to about 50%, by weight of the total weight of the composition, preferably, from about 5% to about 20%, by weight. This composition is a thermosetting resin that contains a dihydrobenzoxazine ring that is formed by the reaction depicted below:

[0004] This component and its process of manufacture is further described in U.S. Patent No. 5,945, 222 (at Col. 2, line 59 to Col. 3, line 62).

[0005] The next additional component of the composition of the present invention is a co-curing agent for the aforementioned resin component(s). Mixtures of compatible co-curing agents can be used. This co-curing agent will be present at from about 5% to about 20%, by weight of the total weight of the composition, preferably from about 5% to about 15%, by weight. Representative co-curing agents include phenol-formaldehyde, cresol-formaldehyde, novolac, novolac/melamine, phosphorylated novolac, triazine-modified novolac resins, dicyandiamide, and the like.

[0006] The compositions of the present invention also contain one or more inorganic filler material(s) at from about 10% to about 50%, by weight. The filler material or materials can be selected from such known fillers as: talc, silica, alumina, aluminum hydroxide, magnesium hydroxide, zinc borate, and the like. A preferred material for use herein is alumina trihydrate.

[0007] While PCT Published Patent Application No. WO 03/029258 teaches that epoxy resins can contain a hydroxy- terminated oligomeric phosphonate as a flame retardant, that PCT application generally shows that the level of such phosphonate needs to be in the neighborhood of from about 20% to about 30%, by weight of the epoxy resin, or higher for acceptable results. No use of filler in such compositions is mentioned.

[0008] In accordance with the present invention, the additional presence of filler has allowed for the use of lower amounts of the phosphonate additive. In Table I, which is given below, Example 7 illustrates that only 10% of the phosphonate was needed. The use of the filler allows for the production of a sufficiently flame retarded epoxy composition, despite the use of lower amounts of phosphonate flame retardant, while still producing a product having good physical properties (such as, higher Tg, better hydrolytic stability, etc).

[0009] Each of the foregoing components of the present composition are individually known to persons of ordinary skill in the art as potential components for epoxy compositions of the present type, and they have been employed in various combinations heretofore, as exemplified by the aforementioned Japanese Patent Publication No. 2001/302,879.

[0010] The reactive phosphonate curing agent that forms a novel and essential additive herein, as compared to prior art approaches that relied upon varying combinations of the previously described components, is present at from about 3% to about 40%, by weight of the total weight of the composition, preferably from about 5% to about 20%, by weight.

[0011] This flame retardant curing agent, as more fully described in PCT International Patent Publication No. WO 03/029258, is an oligomeric phosphonate comprising the repeating unit-OP(O) (R)-O-Arylene- and has a phosphorus content of greater than about 12%, by weight. The phosphonate species in the composition comprise those containing-OH end groups as well, possibly, of those not containing-OH end groups. The preferred R group is methyl, but can be any lower alkyl group.

[0012] By "Arylene" is meant any radical of a dihydric phenol. The dihydric phenol preferably should have its two hydroxy groups in non-adjacent positions. Examples include the resorcinols; hydroquinones; and bisphenols, such as bisphenol A, bisphenol F, and 4,4'-biphenol, phenolphthalein, 4,4'-thiodiphenol, or 4,4'-sulfonyldiphenol. The Arylene group can be 1,3-phenylene, 1,4-phenylene, or a bisphenol diradical unit, but it is preferably 1,3-phenylene.

[0013] This component for the epoxy resin composition of this invention can be made as described in PCT Patent Application 03/029258 by any of several routes: (1) the reaction of an RPOCl₂ with HO-Aryl-OH or a salt thereof, where R is lower alkyl, preferably methyl; (2) the reaction of diphenyl alkylphosphonate, preferably methylphosphonate, with HO-Arylene-OH under transesterification conditions; (3) the reaction of an oligomeric phosphite with repeating units of the structure-OP(OR')-O-Arylene-with an Arbuzov rearrangement catalyst, where R' is lower alkyl, preferably methyl; or (4) the reaction of an oligomeric phosphite with the repeating units having the structure-OP(O-Ph)-O-Arylene with trimethyl phosphite and an Arbuzov catalyst or with dimethyl methylphosphonate with, optionally, an Arbuzov catalyst. The -OH end groups, if attached to Arylene can be produced by having a controlled molar excess of the HO-Arylene-OH in the reaction media. The -OH end groups, if acid type (P-OH), can be formed by hydrolytic reactions. It is preferred that the end groups of the oligomers be mainly -Arylene-OH types.

[0014] The epoxy resin composition of the present invention can contain optional additives as well including the following types of materials: fiber and/or cloth reinforcing additives; release agents; colorants; and the like.

Examples

Materials

[0015] 

Epoxy - bisphenol A type epoxy resin

Novolac - phenol-formaldehyde resin (novolac type) (auxiliary curing agent)

Melamine-novolac - copolymer of phenol, melamine and formaldehyde (auxiliary curing agent)

Phosphor-novolac - phosphorylated phenol-formaldehyde resin (auxiliary curing agent)

ATH - aluminum trihydrate

Phosphonate - reactive phosphonate curing agent where "arylene" is resorcinol

DICY - dicyandiamide (auxiliary curing agent)

AMI-2 - 2-methylimidazole (catalyst)

BDP - bisphenol A bis (diphenyl phosphate) Akzo Nobel brand FYROLFLEX^® BDP

BDP(OH) - Bisphenol A diphenylphosphate

made as described in U.S. Patent No. 3,090,799.

RDP(OH)₂ resorcinol bis(phenylresolcinyl phosphate)

made as described in U.S. Patent No. 5,508,462.

Experimental

[0016] Tg - glass transition temperature measured in TMA experiments as described in IPC-TM-650 protocol.

[0017] UL 94 - flammability rating according to UL 94 vertical protocol (V-0, V-1, V-2)

[0018] PCT - time of exposure to steam in Pressure Cooker Test according to IPC-TM-650 protocol. Water absorption was measured after removal of the specimen from the autoclave.

[0019] Delamination - measured in TMA experiments at 260 or 288° C as described in IPC-TM-650 protocol

[0020] CTE - coefficient of thermal expansion measured in TMA experiments at the temperatures below and above glass transition (<Tg and >Tg respectively). IPC-TM-650 protocol was followed.

[0021] Tables I and II that are reproduced below sets forth a number of formulations that represent embodiments of the present invention, except for formulations 5-8 which do not include a co-curing agent in an amount of 5 to 20%. Table III shows set of comparative formulations.

Table I

Example	1	2	3	4	5	6	7	8
Component
Epoxy, wt. %	45	45	40	40	40	40	40	40
Novolac, wt. %	10	10	5	5
ATH, wt. %	25	25	35	35	35	30	50	50
Phosphonate, wt. %	20	20	20	20	25	30	10	9
DICY								1
AM1-2, wt. %	0.25	0.5	0.25	0.25	0.25		0.25	0.25
Physical property
T.°C	130	130	110	120	140	110	120	130
UL-94, rating	Fall	Fall	V-1	V-0	Fail	Fail	V-0	V-0
PCT, time (min)/pass (fall)	60/F	60/F	30/F	60/F	60/F	60/P	30/P	30/F
water absorption, %	0.4	0.4	0.3	0.3	0.1		0.2	0.3
Delamination at 260°C, min			>60
288°C, min			>60	>60	>60	>60	>60
CTE, <Tg- 106 mm			50	40	40		30	40
>Tg-106 mm			250	250	200		160	195

Table II

Example	9	10	11	12	13	14	15	16
Component
Epoxy. wt. %	30	20	20	20	40	35	20	20
Novolac. wt. %	10	10	5	5
Melamine-novolac, wt. %					15	10	10	5
PBZ, wt. %	15	15	15	15			15	15
ATH, wt. %	25	35	50	50	25	35	35	50
Phospionate, wt. 3%	20	20	10	10	20	20	20	10
AM1-2, Wt. %	0.25	0.25	0.25		0.25	0.25	0.25	0.25

Physical property
Tg°C		140	150	190	130	120	160
UL-94, rating	Fail	V-1	V-0	V-0	Fail	V-1	V-1	V-0
PCT, time (min)/pass (fail)	60/P	90/P	90/P	90/F	120/P	120/P	90/P	90/F
water absorption. %	0.8	1.2	03	0.5	1.0	0.9	1.2	0.2
Delamination at 260°C, min					5	5
288°C, min		>60		>60			>60
CTE<Tg 106 mm		30	30	30	40	35	40
>Tg 106 mm		160	130	160	160	200	165

Table III (comparative)

Example	17	18	19	20	21
Component
Epoxy, wt.%	40	35	35	35	35
Phosphor-novolac, wt. %	15	10
Melamine-novolac, wt. %			10	10	10
BDP, wt. %			20
BDP(OH)2 wt. %				20
RDP(OH)2, wt. %					20
Phosphonate, wt. %	20	20
ATH. wt. %	25	35	35	35	35
AMI-2, wt. %	0.25	0.25	0.25	0.25	0.25
Physical property
Tg °C		100	115	120	120
UL-94, rating	Fail	V-1	Fail	Fail	Fail
PCT, time (min)/pess (fail)	60/F	60/F	60/F	60/F	120/P
water absorption, %	0.4	0.4	0.2	0.3	0.6
Delamination at 260°C, min		>60
288°C, min		20	>60	>60	>60
CTE, < Tg 106 mm		50	50	65	60
> Tg 106 mm		230	240	210	200

Claims

1. A process for curing a composition comprising an epoxy resin and an inorganic filler material, wherein a reactive oligomeric phosphonate comprising a repeating unit OP(O)(R)-O-arylene and having a phosphorous content greater than 12% by weight, wherein R is a lower alkyl and arylene is a radical of a dihydric phenol, is used as curing agent together with 5 to 20% by weight of the total composition of a co-curing agent.

2. The process according to claim 1 wherein the reactive phosphonate is used together with 5 to 15% by weight of the total composition of the co-curing agent.

3. The process according to claim 1 or 2 wherein the epoxy resin is present from 20 to 50% by weight of the total composition.

4. The process according to any one of claims 1-3 wherein the composition comprises a non-halogen containing epoxy resin or a mixture of non-halogen containing epoxy resins.

5. A process for the manufacture of an electronic substrate material comprising the steps of (a) curing a composition comprising an epoxy resin and an inorganic filler material, wherein a reactive phosphonate comprising a repeating unit OP(O)(R)-O-arylene and having a phosphorous content greater than 12% by weight, wherein R is a lower alkyl and arylene is a radical of a dihydric phenol, is used as curing agent together with 5 to 20% by weight of the total composition of a co-curing agent to obtain a cured epoxy resin composition, and (b) using the cured epoxy resin composition in making the electronic substrate material.

6. The process according to claim 5 for the manufacture of a printed wiring board.

Ansprüche

1. Ein Verfahren zum Härten einer Zusammensetzung, das ein Epoxidharz und einen Anorganischen Fülstoff umfasst wobei ein reaktives oligomeres Phosphonat, das eine Wiederholungseinheit OP(O) (R)-O-Arylen umfasst und einen Phosphorgehalt größer als 12 Gew.-% hat, wobei R ein niederes Alkyl ist und Arylen ein Radikal eines zweiwertigen Phenols ist, als Härtemittel zusammen mit 5 bis 20 Gew.-% der Gesamtzusammensetzung eines Co-Härtemittels verwendet wird.

2. Das Verfahren gemäß Anspruch 1, wobei das reaktive Phosphonat zusammen mit 5 bis 15 Gew.-% der Gesamtzusammensetzung des Co-Härtemittels verwendet wird.

3. Das Verfahren gemäß der Ansprüche 1 oder 2, wobei das Epoxidharz von 20 bis 50 Gew.-% der Gesamtzusammensetzung vorliegt.

4. Das Verfahren gemäß einem der Ansprüche 1-3, wobei die Zusammensetzung ein nicht-Halogen-haltiges Epoxidharz oder eine Mischung von nicht-Halogen-haltigen Epoxidharzen umfasst.

5. Ein Verfahren für die Herstellung eines Material für ein elektronisches Substrat, das die Schritte (a) Härten einer Zusammensetzung das ein Epoxidharz und einen Anorganischen Füllstoff umfasst, wobei ein reaktives Phosphonat, das eine Wiederholungseinheit OP(O)(R)-O-Arylen umfasst und einen Phosphorgehalt größer als 12 Gew.-% hat, wobei R ein niederes Alkyl ist und Arylen ein Radikal eines zweiwertigen Phenols ist, als Härtemittel zusammen mit 0 bis 20 Gew.-% der Gesamtzusammensetzung eines Co-Härtemittels verwendet wird, um eine gehärtete Epoxidharz-Zusammensetzung zu erhalten, und (b) Verwenden der gehärteten Epoxidharz-Zusammensetzung bei der Herstellung des Materials für ein elektronisches Substrat umfasst.

6. Das Verfahren gemäß Anspruch 5 für die Herstellung einer gedruckten Leiterplatte.

Revendications

1. Procédé de durcissement d'une composition comprenant une résine époxy et une charge inorganique, dans lequel un phosphonate oligomère réactif comprenant une unité de répétition OP(O) (R)-O-arylène et une teneur en phosphore supérieure à 12 % en poids, où R est un alkyle inférieur et l'arylène est un radical d'un phénol dihydrique, est utilisé comme agent de durcissement en conjugaison avec 5 à 20 % en poids de la composition totale d'un co-agent de durcissement.

2. Procédé selon la revendication 1, dans lequel le phosphonate réactif est utilisé en conjugaison avec 5 à 15 % en poids de la composition totale du co-agent de durcissement.

3. Procédé selon la revendication 1 ou 2, dans lequel la résine époxy est présente dans une quantité de 20 à 50 % en poids de la composition totale.

4. Procédé selon l'une quelconque des revendications 1 à 3, dans lequel la composition comprend une résine époxy ne contenant pas d'halogène ou un mélange de résines époxy ne contenant pas d'halogène.

5. Procédé de fabrication d'un matériau de substrat électronique, comprenant les étapes consistant à (a) durcir une composition comprenant une résine époxy et une charge inorganique, dans laquelle un phosphonate réactif comprenant une unité de répétition OP(O)(R)-O-arylène et une teneur en phosphore supérieure à 12 % en poids, où R est un alkyle inférieur et l'arylène est un radical d'un phénol dihydrique, est utilisé comme agent de durcissement en conjugaison avec 5 à 20 % en poids de la composition totale d'un co-agent de durcissement pour obtenir une composition de résine époxy durcie, et (b) utiliser la composition de résine époxy durcie pour fabriquer le matériau de substrat électronique.

6. Procédé selon la revendication 5 pour la fabrication d'une carte de circuits imprimés.